Inspect the valve seat inserts

(2) Remove the plug (15) from the cylinder

Before installing new v a l v e s o r v a l v e s u s e d

head. Remove the studs (16) from the head. Using

previously, the valve seats in the cylinder head

a guide removal tool, extract the valve guides (17).

should be inspected for proper valve seating. If

previously used valves are to be reinstalled, the

(3) Remove the studs (18). capscrews (19).

valve stems should be cleaned and the valve faces

washers (20), cover (21) and gasket (22).

ground to an angle of 45 When refacing the

(4) Remove the push rods (23) from the

cylinder head.

valves. remove just enough to clean up the face,

removing all evidence of pitting and grooving.

(5) Inspect the valve seat inserts (24 and 25).

(8) Clean the carbon from the valve guides

If loose, cracked or pitted, remove by welding a

using a valve guide cleaning tool. The specified

bead around the inside of the beveled edge. Allow

clearance of the intake valve stem in the valve guide

to cool and lift out the inserts.

is 0.0015 to 0.0033 inch, and should not exceed

(6) Place the cylinder head on end and depress

0.006 inch. If clearances exceed the specified

the springs (29) with a spring compressor. Remove

limits. the valve, valve guide, or both should be

the caps (26), locks (27) and retainers (28).

rfxplaced.

Release the spring compressor and remove the

(9) Inspect the valve seat inserts. If loose,

springs (29) and valves (30 and 31). Mark the

cracked, or pitted. new inserts must be installed.

valves as they are removed to ensure installation in

When new valve seat inserts are installed, or

original positions.

previously used inserts refaced, refinishing must be

c. Cleaning, Inspection and Repair.

done with a valve grinder set. Use the following

(1) Inspect the rocker arm bore for wear. The

procedure to grind the valve seat inserts.

specified clearance between the shaft and the bore

(a) Install the valve seat grinding tool in

is 0.001 to 0.0035 inch and must not exceed 0.005

position with the tool pilot in the valve guide.

inch. If the clearance is greater than the allowable

(b) Use a 45 grinding wheel for refacing

limit, the rocker arm should be replaced. Inspect

the valve seat. Use the 30 grinding wheel for

the machined end (valve stem end) of the rocker

narrowing the intake valve seat to the specified

arms for signs of wear. If they are not excessively

1/16 inch and use the 60 grinding wheel to

worn, the contact surface can be refaced on a lathe.

narrow the exhaust valve seat to 3 / 32 inch.

(2) Inspect the rocker arm shaft for wear and

(c) After the seats have been ground, use a

replace if necessary. Remove the end plugs, and

dial indicator gage to check concentricity of the

clean the oil holes with a solvent and compressed

valve seats relative to the valve guides. Total run

air.

out of the valve should not exceed 0.002 inch.

(3) Clean the cylinder head with a cleaning

(d) Insert the valves in position in the

solvent, removing a l l c a r b o n d e p o s i t s . I f t h e

cylinder head and lap in place, using a fine grain

cylinder head is to be replaced. the parts removed

valve lapping compound. After lapping, contact

from the old head must be thoroughly inspected

between the valves and seats may be checked by

before installing them in a new head. Be sure the

wiping a thin film of Prussian Blue on each valve

water passages in the cylinder head are clean.

scat and setting the valves in place. Bounce each

(4) Inspect both ends of the push rods for signs

valve once on its seat but do not rotate the valve. If

of wear. Polish.out any nicks or score marks. If the

the valve seats were properly ground, a continuous

push rods are bent, twisted, or damaged. they must

thin blue line will be evident around the face of the

be replaced.

valve.

(5) Inspect the flat surface of the valve lifters

d. Reassembly. (fig. 3-7.)

for wear. Replace any worn lifters. Check the lifter

(1) If new valve guides (17) are installed,

bore in the cylinder block and the OD of the valve

insert the upper (chamfered) end of the guide on a

lifter stem. If there is more than 0.0025 inch

guide installing tool. Press the guide into the

clearance, the lifter should be replaced.

cylinder head until the top of the guide protrudes

(6) Inspect the valve springs for cracks. Both

7 / 32 inch above the the top surface of the cylinder

intake and exhaust valve springs when compressed

head. Position all guides to the same depth in the

to a length of 1 27 / 32 inches should exert a

head.

resistance force of 42-47 pounds. When the

(2) Insert the valves (30 and 31) into the

spring is compressed to 1 13 / 32 inches, it should

guides to check for proper clearance between the

have a resistive force of 122- 131 pounds. Spring

valve stems and valve guides. Specified clearance is

free length is 2 3 / 32 inches. Replace any springs

0.0015 to 0.0035 inch. If clearance is less than

that are cracked or weak.

0.0015 inch. ream the guides to obtain proper

(7) Clean the carbon from the valves and valve

clearance. Inside diameter of the valve guide is

seats. Replace the valves if they are cracked, bent,

0.343 to 0.344 inch.

or worn beyond the allowable limits. The specified

(3) If new seat inserts (24 and 25) are to be

limits of the valve stems is 0.3405-0.3415 inch.

3-11